Question: What is the amplitude of $y= 2\cos(7x+5)+1$ ?
Solution: Amplitude in sinusoids of the form $y=a\cos(bx+c)+d$ The amplitude of a sinusoid of the form $y={a}\cos(bx + c) + d$ is equal to $|{a}|$. [How can we justify this given our graphical understanding of amplitude?] Finding the amplitude The amplitude of $y = {2}\cos(7x+5)+1$ is $|{2}|=2$.